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    SDS labs capacitor board hum Mark iii

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    daniel a

    Posts : 8
    Join date : 2013-12-26

    SDS labs capacitor board hum Mark iii

    Post by daniel a on Fri Dec 27, 2013 1:52 pm

    Any ideas as to why an  SDS capacitor  board for a Mark iii would have loud hum 10 seconds after
    turning amp on. Put old quad capacitor back in and amp was fine All parts are in correct position and polarity    soldered points are good.    Hum is from speaker

    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: SDS labs capacitor board hum Mark iii

    Post by GP49 on Fri Dec 27, 2013 1:56 pm

    Probably a bum capacitor. It happens...

    peterh

    Posts : 679
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: SDS labs capacitor board hum Mark iii

    Post by peterh on Fri Dec 27, 2013 2:46 pm

    daniel a wrote:Any ideas as to why an  SDS capacitor  board for a Mark iii would have loud hum 10 seconds after
    turning amp on. Put old quad capacitor back in and amp was fine All parts are in correct position and polarity    soldered points are good.    Hum is from speaker
    Keep the old cap, return SDS cap and order a new cap from tubes4hifi ( or dynakitparts)

    kygeezer

    Posts : 51
    Join date : 2012-11-30

    Re: SDS labs capacitor board hum Mark iii

    Post by kygeezer on Fri Dec 27, 2013 3:57 pm

    Don't give up on the SDS board! I rebuilt two Mark IIIs and used SDS boards on both. They are both dead quiet. Be sure you follow the grounding instructions and be sure you don't have any solder bridges which are easy to do on those boards. Good luck!

    daniel a

    Posts : 8
    Join date : 2013-12-26

    Re: SDS labs capacitor board hum Mark iii

    Post by daniel a on Fri Dec 27, 2013 7:24 pm

    The instructions from triode electronics said nothing about grounding the board. Called them and they recommended grounding the board. said their instructions need updated  really

    GP49

    Posts : 735
    Join date : 2009-04-30
    Location : East of the sun and west of the moon

    Re: SDS labs capacitor board hum Mark iii

    Post by GP49 on Sat Dec 28, 2013 12:33 am

    daniel a wrote:The instructions from triode electronics said nothing about grounding the board. Called them and they recommended grounding the board. said their instructions need updated  really


    RECOMMEND grounding the board? The capacitors MUST have their low side grounded. What am I missing here???

     What a Face affraid confused scratch

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